Apparent contraction of edge angles

The corner effect, the Munsterberg illusion, and the Cafe Wall illusion are explained by a model postulating that the corner effect is an orientation illusion specific to corner edges and that the perceived orientations of th ese edges are shifted toward angle contraction. It is also assumed that the effect is greatest when the corner edges show the same or similar edge con trast at the corner. This model yields three new types of illusions: the 'c heckered illusion', the 'illusion of shifted gradations', and the 'illusion of striped cords'. Each of them gives many variations making a three-dimen sional impression.